With the wide spread of electronic appliances including laptop computers, cellular phones, etc., there has recently been a rapid increase in demand for secondary batteries. A secondary battery is composed of an anode, a cathode, an electrolyte, and a separation membrane. Manganese oxides are widely used as the main materials for the cathode. Demand for secondary batteries is now rapidly increasing, with the consequent increase in materials necessary for the production of secondary batteries.
Manganese oxides are widely used as electrode materials for secondary batteries. A manganese oxide is a compound composed of manganese and oxygen as its name implies, and examples thereof include manganese oxide (II) (MnO), trimanganese tetraoxide (Mn3O4), manganese oxide (III) (Mn2O3), manganese oxide (IV) (MnO2), and manganese oxide (VII) (Mn2O7). As a cathode material for secondary batteries, trimanganese tetraoxide (Mn3O4) or manganese oxide (III) (Mn2O3) may be available. Recently, trimanganese tetraoxide (Mn3O4) has become the predominant choice over manganese oxide (III) (Mn2O3) due to production cost. However, almost all the amount of trimanganese tetraoxide (Mn3O4) needed as an electrode material for secondary batteries is imported.
Recovery of manganese compounds is described in many documents. For instance, Korean Patent No. 10-1052192 discloses a method for recovering manganese compounds from electric arc furnace dust. In detail, Korean Patent No. 10-1052192 describes the recovery of manganese compounds from electric arc furnace dust, with the concomitant recovery of ammonium sulfate according to acids and bases used for the production of alkaline metal compounds and manganese compounds. However, the trimanganese tetraoxide recovered by the method has a low purity of about 60%, and thus it is difficult to recover high-purity trimanganese tetraoxide by the method.
Korean Patent Application Unexamined Publication No. 2001-0113176 describes a method for producing high-purity manganese oxide by low-temperature pyrolysis of manganese nitrate. In detail, Korean Patent Application Unexamined Publication No. 2001-0113176 addresses the production of trimanganese tetraoxide by reductively roasting a manganese material, leaching nitric acid, primarily purifying to remove impurities, partially degrading manganese nitrate, washing the manganese dioxide produced in the partial degradation process, sintering the washed manganese dioxide to manganese oxide, and pulverizing. The trimanganese tetraoxide produced by this method is 71.3% pure, so that the method is difficult to apply to the preparation of high-purity trimanganese tetraoxide.